Dlesex



(No Model.)

G. BOWRON & W. HIBBERT.

MANUFACTURE OF CARBON FILAMENTS FOE INUANDESGENT LAMPS.

v No. 304,901. Patented Sept. 9, 1884.

F102? FIGS.

FI.C.I. FICV.2. no.3.

NlTE rains Arniwr arrest GEORGE BOYVRON AND XVALTER HlBBERT, OF LONDON,COUNTY OF MID- DLESEX, ENGLAND.

MANUFACTURE OF CARBON FILAMENTS FOR INCANDESCENT LAMPS.

SPECIFICATION forming part of Letters Patent No. 304,901, datedSeptember 9, 1884.

Application filed October 17, 1883. (No specimens.) Patented in EnglandFebruary 12, 1883, No. 764, and in France August 9, 1883, No. 156,962.

To aZZ whom it may concern.-

Be it known that W6,GEORGE BOWRON and VVALTER' HIBBERT, subjects of theQueen of Great Britain and Ireland, and residing at London, in thecounty of Middlesex, England, have invented certain new and usefulImprovements in the Manufacture of Carbon Filaments for IncandescingElectric Lamps,

(for which we have received Letters Patent in Great Britain, No. 764,dated February 12, 1883, and have applied for Letters Patent in France,August 9, 1883;) and we do hereby declare that the following is a full,clear, and exact description of the invention, which will enable othersskilled in the art to which it appertains to make and use the same. Ourinvention has for its object the production of carbon filaments forincandescing electric lamps of a more homogeneous structure than hasbeen heretofore attainable, whereby increased durability and greaterilluminating power per unit of surface will be obtained; and it consistsin making such filaments of a mixture of carbon in a very fine state ofdivision and a solution of sugar or other viscous liquid of anorganicnature, or holding organic substances in solution, in the mannerand by the means substantially as hereinafter described.

In carrying out our said invention we take graphite or lamp-black, orvegetable black, and mix-therewith the viscous liquid, by preference astrong solution of sugar, the two ingredients (the carbon and thesolution of sugar .or other viscous liquid) being employed in suchrelative proportions that their commixture shall form a pastyconsistence. As this condition is the result which is to be sought, theexact proportions of the two ingredients may be readily arrived at bytesting in small quantities, it being obvious that as the proportionsmust necessarily be varied according to the nature and state of division.of the carbon it is not possible to give definite proportions whichwill be applicable in all cases. It should be observed, however, that nomore of the Viscous liquid should be used than is necessary to make ahomogeneous paste presenting a dry appearance. We have found thefollowing approximate proportions to give good results in practice, viz:With the use of graphite in a very fine powder a quantity of solution ofsugar may be employed equal to, say, about sixty percent. of the weightof graphite used, the solution containing, say, about sixty to seventyper cent. of sugar. \Vith lamp-black or vegetable black, also in a veryfine powder, a larger proportion of solution of sugar may beemployed--viz., about two hundred per cent. of the weight of lamp-blackor vegetable black usedthe solution of sugar being of the same strengthas before.

In lieu of employing graphite or lampblack or vegetable black, charcoalderived from sugar or any equivalent carbon-yielding substance may beused; but as the results so far obtained with it havebecn inferior tothose obtained with graphite or lamp-black or vegetable blaclgwe do notrecommend its use, but

prefer to employ the forms of carbon first V mentioned.

I11 lieu of using a solution of sugar we may employ other viscousliquids of an organic nature, or holding organic substances in s0lution.For example, when vegetable black is employed, a solution of resin inturpentine may be used; but in this case we have always found itadvantageous to add to the carbon used a proportionate quantity ofsugar. This is most conveniently done by mixing a suitable quantity ofsolution of sugar wit-h the carbon and then evaporating to dryness, thecarbon and granular sugar resulting being afterward mixed with thesolution of resin in turpentine. Good results have been obtained bymixing with the vegetable black a quantity of pure sugar equal to aboutthirty per cent. of the weight of vegetable black used, the sugar beingadded in the form of a weak solution, containing,say, about five percent. of sugar, and after evaporation mixing the vegetable black andsugar with a quantity 'of solution of resin in turpentine equal to, say,about ninety per cent. of the weight of the mixture of vegetable blackand sugar used,

the solution containing, say, from about forty I able former in such amanner as to apto fifty parts of resin in one hundred parts of thesolution.

We desire to note here that in theforegoing stated proportions ofingredients we have given such figures as will enable the compound to beworked at ordinary temperaturesthat is to say, without heatingwhich is apoint of considerable practical advantage. The carbon and solution ofsugar or other viscous liquid having been mixed together in suitable proportions, as before mentioned, so as to form a pasty consistence, thesame is introduced into a vessel or receptacle having a very minuteorifice, through which the material is forced by means of a plunger, andissues in the form of a continuous and flexible filament.

The accompanying drawings illustrate some convenient forms of apparatusto be used in the manufacture of the filaments.

Figure 1 represents avertical section of one form of apparatus. A is ahollow cylinder,the interior a of which is bored true, smooth, andcylindrical for the greater part of its depth, for the reception of aplunger, B,but slightly conical at its lower end, for the insertion of aconical plug, G, the chamber b of the latter terminating in a veryminute orifice, c. In operating with the apparatus, the plug 0 being inits place and the plunger B withdrawn,a suitable quantity of the mixtureof carbon and solution of sugar or other viscous liquidin the conditionof apasty consistence is introduced into the interior a of the cylinderA; the plunger B is then inserted and pressure applied at its upper endby means of a screw-press or otherwise, whereby the material is forcedout through the orifice c, and issues in the form of a continuous andflexible filament. This arrangement is adapted for the production ofsolid filament-s. \Vhen tubular filaments are required,they may beproduced by the addition of a filamentous core to the die or plunger,thecore occupying the center of the orifice.

Fig. 2 is a vertical section of an apparatus intended for the productionof tubular filaments. A is the cylinder, with its bore a terminating atits lower end in a conical portion,in which are fitted two plugs, O C, ashort distance apart, so as to leave a space, d, between them. The plug0 is formed with an orifice, 0, while the plug 0 carries a filamentouscore, 0, which occupies the center of the orifice c, grooves or passagesf being provided on the periphery of the plug 0 (see detail Fig. 2) forthe passage of the material. The operation is performed by theapplication of pressure to a plunger, B, as before.

Fig. 3 shows a similar apparatus in which the plug 0 is dispensed with,the orifice c being formed in the cylinder A. The plug C, (shown indetail in Fig. 8,) with its pendent filamentous core a, is used asbefore. The continuous flexible filament, whether solid or tubular,issuing from the appa atus, is lightly wound or allowed to fall aroundor over a suitproximate to the shape of the filaments and be then cut upor otherwise severed.

Figs. 4 and 5 represent, respectively, an elevation and section (drawnto a reduced scale) of a former, D, by turning which and moving itslightly longitudinally as the filament g descends from its point ofegress A the filament will become lightly wound round it, the severalfilaments being subsequently severed at 71 or the device shown on areduced scale in Figs. 6, 7, 8, and 9 may be conveniently adopted, ofwhich Figs. 6, 7, and 8 are diagrammatic sectional views, illustratingthree different positions, and Fig. 9 is an elevation. A represents thepoint of egress of the filament from its cylinder, and D the former. Thecontinuous filament first descends down one side of the former D, asshown in Fig. 6. The former is then moved to the left, so that thefilament will descend in a loop form down the opposite side, as shown inFig. 7, after which the former is moved to the right and the loopdescends down the other side, as shown in Fig. 8, and so on insuccession until as the former is gradually moved longitudinally thewhole length of the former is covered with loops, which only requiresevering to produce filaments of a form suitable for use in incandescinglamps.

It is obvious that the shape of the formers is to be varied to. suit theform of filaments required. The filaments, having been cut or severed,may be at once subjected to the action of the carbonizing apparatus; or,as we prefer, they are first allowed to dry by exposure to the air andthen carbonized. The filaments are then ready for connection to theleading-in wires of the lamp, to which they may be attached by adhesionand carbonization of a small quantity of the paste of which thefilaments are made, or in any other suitable manner.

If preferred, the filaments may be attached to the leading-in wiresbefore carbonization; or the continuous filament may be first dried andcarbonized, and afterward cut up or severed into lengths for thefinished filaments.

If desired, the filaments may be placed in an atmosphere ofhydrocarbon-vapor and raised to incandescenee in the well-known manner.

The carbon filaments may be employed in exhausted bulbs in the usualmanner.

Having fully described our invention, what we desire to claim and secureby Letters Patent is- The hereinbeforedescribed improvement in the artof manufacturing carbon filaments for incandescing lamps from a mixtureof carbon in a fine state of division with a solution of sugar or otherviscous liquid of an organic nature or holding organic substances insolution, which consists in squeezing said mixture, in pasty condition,through a die, whence it issues in the form of a flexible continuousfilament, depositing said filament as it issues names to thisspecification in the presence of 10 upon or around a former in the shapeof a setwo subscribing Witnesses. ries of connected loops approximatelyof the shape required for, the finished ineandeseing 5 filaments, andsubsequently separating said x M loops from one another and earbonizingthe Witnesses: same, substantially as and for the purposes set THOMASJOHN HANDFORD, forth. 7 ALFRED MAXWELL,

In testimony whereof we have signed our Both of 42 SouthmnptonBm'ldings, London.

